/*
 *  Copyright 2013 National Institute of Advanced Industrial Science and Technology
 *  
 *  Licensed under the Apache License, Version 2.0 (the "License");
 *  you may not use this file except in compliance with the License.
 *  You may obtain a copy of the License at
 *  
 *      http://www.apache.org/licenses/LICENSE-2.0
 *  
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 */

package org.sss.common.io;

import java.io.IOException;
import java.util.List;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.sss.common.DataReceiver;
import org.sss.mapreduce.Configuration;
import org.sss.mapreduce.DB;
import org.sss.mapreduce.GroupID;
import org.sss.mapreduce.SssException;
import org.sss.mapreduce.StorageNode;

/**
 * .
 * NOTE: This class used by only map operation.
 */
public class RestrictedFlatDataReader extends AbstractFlatDataReader{
  @SuppressWarnings("unused")
  private static Logger logger = LoggerFactory.getLogger(RestrictedFlatDataReader.class);

  public RestrictedFlatDataReader(Configuration conf,
                                  StorageNode node,
                                  GroupID gid,
                                  int subhash,
                                  DataReceiver<List<byte[]>> next) throws SssException {
    super(conf, node, gid, subhash, next);
  }

  /**
   * .
   * NOTE:This method should be called for TTDB with restricted access.
   */
  @Override
  protected void issueCommands(IOThread iot) throws SssException, IOException {
    DB db = iot.getDB(node);
    int count_max = iot.getIOGetBatchCount();
    final byte[] prefix = KeyFormatter.getPrefix(getSource(), subhash);
    final List<byte[]> allkeys = db.fwmkeys(prefix, -1);
    final int count_target = allkeys.size();
    boolean done = count_target == 0;
    int count_sofar = 0;
    while (!done) {
      checkCanceled();
      final int count_tmp = Math.min(count_target - count_sofar, count_max);
      byte[][] ks = new byte[count_tmp][];
      for (int i=0; i<count_tmp; i++) {
        ks[i] = allkeys.get(count_sofar + i);
      }
      List<byte[]> kvs = db.getlist(ks);
      final int count_read = kvs.size();
      count_sofar += count_read / 2;
      if (isDestructiveRead() && count_read > 0) {
        db.outlist(ks);
      }
      countup(kvs);
      if (count_read > 0) {
        next.put(kvs);
      }
      done = count_target == count_sofar;
    }
    next.close();
  }
}
